Automatic self-addressing method for wired network nodes

ABSTRACT

A method and system for addressing nodes in a multi-drop wired network are disclosed. In an embodiment nodes communicate via a two-way communication bus. Upon receipt of an address command, a first node assigns itself a first address, closes a switch to activate an output port of the first node to enable a second node to receive communications from the first node, and sends a second address onto the two-way communication bus. The second address is received by all previously addressed nodes, including a controller if used, as well as the second node, which is as yet unaddressed. Upon receipt of the second address, the second node repeats the process. If a node does not receive an acknowledgement that a subsequent node has addressed itself, that node deactivates its output port and terminates the network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/172,906 filed on Apr. 27, 2009, which is incorporated herein byreference.

FIELD OF DISCLOSURE

The field of this disclosure relates to operation of wired networks ofnodes, and in particular to the automatic self-addressing of the nodesin wired networks.

BACKGROUND

In a wired network, node addressing can present a challenge. Often, thisaddressing is manually set or manually correlated with the installedlocation of the devices so that networked equipment can be properlyconfigured for its intended function. For example, in an EIA-RS485network each node can be configured with a unique address and both endsof the communication bus terminated with matching resistors to enablereliable communication and maximum network length. In the past, theinstaller or commissioning agent would manually set each address andeither know or search to determine which node is physically first andlast to successfully terminate the EIA-RS485 bus. As another example, ina DALI network the user addresses each node, typically via some type ofDALI controller and software. This process can be very confusing toaverage users and frequently results in either a non-functioning systemor a system that requires additional expertise and expensive technicalsupport to troubleshoot.

Previous attempts to solve the addressing problem for multi-dropnetworks have involved either the addressing of devices at the factorybased on their planned installation location or the use of randomaddressing schemes. Factory addressing can eliminate some of theproblems and hassle associated with addressing networks in the field,but requires a large amount of coordination between the factory andinstaller before the units are shipped. This coordination addssignificant costs and lead time to products and introduces manyopportunities for error and further hassle in the manufacturing,installation, and maintenance processes (i.e. incorrect addressing orlabeling at the factory, installation in the wrong location, needingspecial equipment to address a replacement station if one fails, etc).Random addressing, which can be initiated either through software or aphysical activation by the user, eliminates the need for physical wheelsor switches that would otherwise be required to manually set theaddress, but requires a lengthy commissioning procedure in which thelocation of each randomly addressed device is “found” and entered into adatabase so that it can be properly identified and configured for itsintended use.

SUMMARY

In one embodiment, a new addressing method and associated circuitryenables any and all nodes connected on a multi-drop wired network toautomatically self-address and optionally also self-terminate (ifapplicable) based on their sequential electrical location in thenetwork. The automated addressing scheme described herein can be appliedto any multi-drop wired network or communication protocol and with anynetworked device. However, DALI and EIA-RS485 networks are presentedhere as embodiments for illustration purposes only. One of ordinaryskill in the art will recognize, though, that other networks includingbut not limited to those comprising EIA-RS232, EIA-RS422, EIA-423, I2C(inter-integrated circuit), or CAN (controller-area network) nodes arealso possible within the embodiments described herein.

BRIEF DESCRIPTION OF DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are better understood when the following Detailed Descriptionis read with reference to the accompanying drawings, wherein:

FIG. 1 illustrates a prior art DALI network configuration.

FIG. 2 illustrates a prior art RS485 network configuration.

FIG. 3 illustrates a DALI network configuration in an exemplaryembodiment.

FIG. 4 illustrates an RS485 network configuration in an exemplaryembodiment.

FIG. 5 illustrates a flowchart of an addressing method in an exemplaryembodiment.

FIG. 6 illustrates a flowchart of an addressing method in an exemplaryembodiment.

FIG. 7 illustrates a DALI system in an exemplary embodiment.

FIG. 8 illustrates a single slave DALI node in an exemplary embodiment.

FIG. 9 illustrates waveforms in an exemplary embodiment.

FIG. 10 illustrates an RS485 bus in an exemplary embodiment.

FIG. 11 illustrates a DALI network configuration in an exemplaryembodiment.

FIG. 12 illustrates an RS485 network configuration in an exemplaryembodiment.

DETAILED DESCRIPTION

Detailed embodiments are disclosed herein. However, it is to beunderstood that the disclosed embodiments are merely exemplary and thatdifferent embodiments are possible. The figures are not necessarily toscale, and some features may be exaggerated or minimized to show detailsof particular components. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a basis for the claims and as a representative basis forteaching one skilled in the art to variously employ the presentdisclosure.

FIG. 1 illustrates a prior art DALI network configuration. DALI network100 typically comprises a power supply 101, a controller 102, one ormore nodes 103 a, . . . , 103 x, and a communication bus 104. Each node103 a-x comprises a DALI port, which itself comprises an input port andan output port, as exemplified by wires 105 a and 105 b associated withnode 103 a, through which it connects to the communication bus 104.Preferably these wires are short and are inside the electrical or DALInode box. Similarly, FIG. 2 illustrates a prior art EIA-RS485 networkconfiguration. RS485 network 200 typically comprises one or more nodes201 a, . . . , 201 x as well as a communication bus 202. Each node 201a-x comprises an RS485 port, which itself has an input port and anoutput port, as exemplified by 203 a and 203 b associated with node 201a, through which it connects to the communication bus 202. In the past,these typical prior art networks have been addressed as discussed in thebackground section above.

FIG. 3 illustrates an embodiment of a modified DALI networkconfiguration for use with embodiments disclosed herein. In thisembodiment, DALI network 300 comprises a power supply 301, an optionalcontroller 302, one or more nodes 303 a, . . . , 303 x, and acommunication bus 304 permitting two-way broadcast communication betweennodes connected to the network 300. Each node 303 a-x has input andoutput ports, as exemplified by 305 a and 305 b associated with node 303a respectively, through which it connects to the communication bus 304.In this embodiment, input port 305 a and output port 305 b embody aseries switch 306 that activates output port 305 b thereby permittingnode 303 b to connect via the communication bus 304 to DALI power supply301, DALI controller 302 (if used), and node 303 a.

FIG. 4 illustrates an embodiment of a modified RS485 networkconfiguration for use with embodiments disclosed herein. In thisembodiment, RS485 network 400 comprises one or more nodes 401 a, . . . ,401 x as well as a communication bus 402. permitting two-way broadcastcommunication between nodes connected to the network 400 Each node 401a-x has an input port and an output port, as exemplified by 403 a and403 b associated with node 401 a respectively, through which it connectsto the communication bus 402. In this embodiment, input port 403 a andoutput port 403 b embody switches 404 a and 404 b that activate outputport 403 b thereby permitting node 401 b to connect via thecommunication bus 402 to node 401 a.

The addition of a series switch device, as exemplified by series switch306, to each node 303 a-x of a DALI network provides a DALI hardwareimplementation suitable for use with a method of automatic addressing.Similarly, the addition of one or more series switch devices, asexemplified by series switches 404 a and 404 b, to each node 401 a-x ofan RS485 network provides an RS485 hardware implementation suitable foruse with a method of automatic addressing. The switches can be solidstate components like transistors (BJTs), MOSFETs, SCRs, TRIACs(thyristors), etc, or electro-mechanical relays.

The series switch (or switches) in each node acts to split the networkinto a number of individual sections which can be dynamically separatedand rejoined as part of the addressing procedure. For example, in FIG.3, initially the series switch in each node, as exemplified by switch306, is in the open or OFF position; so only the first node 303 a iselectrically connected to the DALI controller 302 and can “communicate”with it. When the DALI controller 302 initiates the self addressprocedure by sending a “start self address and start with x address”command, the first node 303 a receives that message, assigns itself theaddress from the received message, closes or turns ON series switch 306,which activates output port 305 b, and sends a “start self address andstart with x+1 address” message through output port 305 b ontocommunication bus 304. Due to the settings of switches to the OFFposition in the other network nodes, which results in deactivating theirrespective output ports, the only unaddressed node that receives the“start self address and start with x+1 address” is the next node 303 b.However, all previously addressed nodes (such as node 303 a), whoseoutput ports have been activated by closing their respective switches,as well as the controller, likewise receive the command. Upon receptionof this message, the second node 303 b then assigns the “x+1” address toitself, closes or turns ON its series switch 307 and communicates x+2address onto the communication bus 304, resulting in the next node 303 cbeing the only unaddressed node to receive the command, and so on. Theseries switch stays closed in each node once it has been addressed,thereby making a standard and complete communication network where nodesare connected in parallel. The series switches will remain in the ON(closed) position until the nodes again receive the DALI command fromthe controller 302 to initiate the self-address process. Upon receptionof this command, each node opens or turns OFF the series switch and theprocess of self addressing repeats again. This process could be repeatednumerous times and/or periodically to ensure that the assigned addressis valid. Similarly, a confirmation message with whatever information isdeemed most appropriate by the designer can be sent by the nodes as theyare addressed, or after the addressing is complete, so that controller302 can compare nodes currently online and addressed with those thathave been online and addressed previously. This addressing can besequential (x+1) or any other suitable incremental or decremental logic.

An EIA-RS485 example embodiment of an automatic addressing scheme can beimplemented with an electromechanical relay. Any voltage drop across theseries switch preferably is limited due to the low operating voltage ofthis system, which effectively precludes the use of a solid state switchfor all EIA-RS485 networks except those used with relatively few nodes.Naturally, if a solid state switch were available with a very low onstate resistance, it could be used for networks with higher quantitiesof nodes. The system can be implemented with a single DPDT (double poledouble throw) relay or two SPDT (single pole double throw) relays.Similarly, it will be obvious to those skilled in the art that anyalternate components which allow the terminating resistor or networkwires to be connected and disconnected by the controller (not shown),including those which are integrated into a transceiver chip or othercomponents, could be used in the circuit. Single DPDT relays are used inthis example for simplicity of describing the system. Initially, theseries switch, as exemplified by switches 404 a and 404 b in eachEIA-RS485 node 401 a-x, are in the OFF (open) position. The terminatingand bias resistors (not shown) of every node 401 a-x are connected inthis OFF position. This allows only the first EIA-RS485 node 401 a tocommunicate with the controller (master) (not shown). The controllersends “start self addressing and start with x address”. Similarly to theDALI example, the first node 401 a in EIA-RS485 bus receives thatsignal, assigns “x” address to itself, closes the switches 404 a and 404b, which activate output port 403 b, and communicates “x+1” addressthrough output port 403 b onto the communication bus 402. The onlyunaddressed node that receives this command is the next node 401 b.However, all previously addressed nodes (such as node 401 a), whoseswitches have been closed, also receive the command. If the first node401 a receives acknowledgement that the second node 401 b is present,then its switches 404 a and 404 b will remain in the ON position.Otherwise, switches 404 a and 404 b return to the OFF position and theEIA-RS485 bus terminates with node 401 a. However, if the first node 401a receives the acknowledgement, switches 404 a and 404 b remain in theON position, the second node 401 b assigns “x+1” address to itself,closes its switches 405 a and 405 b, and sends “x+2” address to the nextnode 401 c. The process continues until all of the nodes 401 a-x onEIA-RS485 network are addressed and the last node 401 x terminates theEIA-RS485 bus.

FIG. 5 illustrates a flowchart for an embodiment of an automaticaddressing method 500 implemented at a controller unit. At block 501,the method engages any terminating and biasing resistors as needed. Oncethis step is complete, the controller transmits a command to tell thefirst node to start the self-addressing procedure and which address tostart with, e.g. start at address “x.” At block 503 the controllermonitors the communication bus to detect if a command to start addressat, for example, “x+n,” is sent by any of the nodes. This monitoringoccurs for a predetermined period of time as set by a timer. If atdecision block 504, the timer has not expired, the controller continuesmonitoring. If at decision block 503 the timer has expired, then atblock 505 the controller sends a command to terminate theself-addressing procedure. The number of nodes that have been addressedis then determined by the controller based on the difference between theinitial start address and the last address sensed by the controller ashaving been sent onto the bus. In the example here the controllerdetermines the number of nodes to be “n” where “x+n” is the last addressdetected by the controller in a command sent by a node and “x” is theinitial start address.

FIG. 6 illustrates a flowchart for an embodiment of an automaticaddressing method 600 implemented at a network node. At block 601, themethod begins by setting the switch to the off position periodically.Similarly, at block 603 the method periodically engages the terminatingand biasing resistors, if used. At decision block 603 the nodeascertains if it has received a start address at address “x” command. Ifnot, the method returns to block 601. If it has received a start addresscommand, then at block 604 the node sets its serial switch to the ONposition and disengages any terminating and biasing resistors used. Thenat block 604 the node transmits a start address at, for example address“x+1” command. At decision block 606 the node ascertains if a command tostart address at, for example, “x+2,” is sent by any of the other nodeswithin a predetermined period of time. If at decision block 606, thenode ascertains that the command has been sent, the node keeps itsseries switch in the ON position and the method ends. If at decisionblock 606 the node does not ascertain that the command was sent withinthe predetermined time period, then at block 607 the node engages anyterminating and biasing resistors and at block 608 it returns its seriesswitch to the OFF position, in which case the node becomes theterminating node of the network and the method ends.

FIG. 7 shows an exemplary embodiment of a DALI network implementation700 comprising a master power supply and controller 701 and slave DALInodes 702 a, . . . , 702 d. In this embodiment the series switch used isa P-channel MOSFET. The main physical characteristic of this componentis low Rds_on which is necessary to keep the voltage drop across thisdevice very minimal. Another way to completely eliminate this drop is touse an electromechanical relay. The main advantage of the use of a solidstate switch over a relay is cost, but it does have the disadvantage oflosing the polarity insensitive wiring feature of the slave DALI node.An electromechanical relay can be used as an alternative to preserve theDALI slave polarity insensitive wiring feature. FIG. 8 shows a close upschematic of a single DALI slave node 800. FIG. 9 presents waveforms901-905 confirming the automated addressing scheme functionality.

FIG. 10 shows an exemplary embodiment of an EIA-RS485 networkimplementation 1000 comprising a master/controller 1001 and four RS485slave nodes 1002 a, . . . , 1002 d, where the slave nodes use DPDTrelays.

FIGS. 11 and 12 illustrate extensions of the network configurations ofFIGS. 3 and 4 respectively to self-explanatory hybrid topologies. Inthese figures a “group” refers to a subnetwork comprising one or morenodes, so that use of a group node, such as group #A node 1103 a,results in both a main network in which node 1103 a is a slave node anda subnetwork, which in this embodiment comprises nodes 1103 a, 1103 a 1,1103 a 2, 1103 a 3, and so on, in which node 1103 a is a master node ora controller. As hybrid topologies are well known, one of ordinary skillin the art will understand how to extend embodiments of the invention tooperate with such topologies through use of an appropriate addressingprotocol in which node 1103 a, after self-addressing, closes theappropriate switches and communicates a next address onto communicationbus 1104 and also communicates an appropriate next subaddress ontocommunication bus 1107. For example, the group node could send a commandto “start self address and start with Ax” onto communication bus 1107.One of ordinary skill in the art will recognize that subaddressing canbe accomplished in a variety of ways. The hybrid topology embodimentillustrated in FIG. 12 operates similarly.

In these illustrative embodiments, the master or controller knows orlearns the existence of each slave node and the address of that node.Each node can be programmed to respond to certain commands to identifyitself in addition to provide its own address. For example, the noderesponse converted from digital to plain English language could be “I'mup and running, my address is xxxxxxx, I'm occupancy sensor, and I'm thelast node on the network so the EIA-RS485 bus is terminated here”.

General

Embodiments of the present disclosure may comprise systems havingdifferent architectures and methods having different information flowsthan those shown in the Figures. The systems shown are merelyillustrative and are not intended to indicate that any system component,feature, or information flow is essential or necessary to any embodimentor limiting the scope of the present disclosure. The foregoingdescription of the embodiments has been presented only for the purposeof illustration and description and is not intended to be exhaustive orto limit the disclosure to the precise forms disclosed. Numerousmodifications and adaptations are apparent to those skilled in the artwithout departing from the spirit and scope of the disclosure.

1. A method of assigning an address to a node of a multi-drop wirednetwork, wherein each node of the multi-drop wired network can connectto a two-way communication bus via an input port and an output port, themethod comprising: receiving at an input port of a first node a firstaddress, where the input port of the first node is connected to thecommunication bus; assigning the first address to the first node;activating an output port of the first node to enable a second node toreceive communications from the first node via the communication bus;determining a second address based on the first address; and sending thesecond address onto the communication bus via both the input port of thefirst node and the output port of the first node.
 2. The method of claim1 further comprising receiving an address subsequent to the secondaddress at the first node via the communication bus.
 3. The method ofclaim 1 further comprising receiving the second address at a controller.4. The method of claim 1 wherein activating an output port of the firstnode to enable a second node to receive communications from the firstnode via the communication bus comprises closing one or more switches.5. The method of claim 4 wherein the one or more switches are selectedfrom a group comprising a solid state switch and an electromechanicalrelay.
 6. The method of claim 1 wherein the first node is selected froma group comprising a DALI node, an EIA-RS485 node, and EIA-RS232 node,an EIA-RS422 node, an EIA-RS423 node, an inter-integrated circuit node,and a controller-area network node.
 7. The method of claim 1 furthercomprising deactivating the output port of the first node andterminating the multi-drop wired network at the first node.
 8. Themethod of claim 1 further comprising deactivating the output port of thefirst node in response to a message received from a controller via thecommunication bus.
 9. The method of claim 8 wherein a message receivedfrom a controller via the communication bus is received periodically.10. The method of claim 1 further comprising deactivating the outputport of the first node and biasing the multi-drop wired network at thefirst node.
 11. The method of claim 1 wherein the first address is sentonto the communication bus by a controller.
 12. The method of claim 1further comprising receiving at an input port of the second node thesecond address, where the input port of the second node is connected tothe communication bus; assigning the second address to the second node;sending a response message via the communication bus from the secondnode to the first node.
 13. The method of claim 1 further comprisingsending a message via the communication bus from the first node to acontroller.
 14. The method of claim 1 wherein the first node is a groupnode, the method further comprising: activating a second output port ofthe first node to enable a third node to receive communications from thefirst node via a second two-way communication bus; determining a thirdaddress; and sending the third address onto the second communication busvia the second output port of the first node
 15. A system for addressingone or more nodes of a multi-drop wired network comprising: a controllerconnected to a two-way communication bus; a plurality of nodes, eachhaving an input port and an output port for connecting to thecommunication bus; at each node, one or more switches connecting theinput port of the node to the output port of the node; wherein thecontroller communicates a first address via the communication bus to afirst node, which connects to the communication bus through an inputport of the first node; the first node activates the output port of thefirst node by setting one or more switches between the input port of thefirst node and the output port of the first node to the ON position; andthe first node communicates a second address onto the communication busthrough both the input port of the first node and the output port of thefirst node.
 16. The system of claim 15 wherein the plurality of nodes isselected from a group comprising DALI nodes, EIA-RS485 nodes, EIA-RS232nodes, EIA-RS422 nodes, EIA-RS423 nodes, inter-integrated circuit nodes,and controller-area network nodes.
 17. The system of claim 15 furthercomprising a group node having an input port connected to thecommunication bus, a first output port for connecting to thecommunication bus, and a second output port connected to a secondtwo-way communication bus; at the group node, one or more switchesconnecting the input port of the group node to the first output port ofthe group node; wherein the group node receives through the input portof the group node connected to the communication bus a third address;the group node activates the first output port of the group node bysetting one or more switches between the input port of the group nodeand the first output port of the group node to the ON position; thegroup node communicates a fourth address onto the communication busthrough both the input port of the group node and the first output portof the group node; and the group node communicates a fifth address ontothe second communication bus through the second output port of the groupnode.
 18. The system of claim 15 wherein the first node receives anaddress subsequent to the second address via the communication bus.